The invention relates to heaters in general, and more particularly to improvements in electric heaters, especially portable fan heaters (also called heater blowers).
A portable fan heater has a housing for a heating unit and a rotary impeller which draws air into and conveys air through the housing and past the heating unit to discharge heated air by way of one or more openings or to merely circulate air in the area around the heater. The heating action can be regulated by changing the number of active heating elements and/or by changing the intensity of heat which is emitted by the active heating element or elements. As a rule, the heating elements are electric resistance heaters which are often mounted on a star-shaped array of insulating plates. Each resistance heater comprises a normally convoluted wire which is heated in response to connection with a source of electrical energy. The means for regulating the intensity of heating action includes suitable switches or other regulating elements which enable the user to elect one of two or any one of more than two (normally three) different heating actions. The rotary impeller is mounted in the housing and is driven by an electric motor to circulate air which distributes the generated heat in one or more desired directions.
A drawback of conventional heaters which employ heating elements in the form of resistance heaters is that the cost of such heating elements is high and their installation in the housing of the heater is a complex and time-consuming operation. Thus, it is necessary to coil the wire in order to form individual heating elements, and such elements must be mounted on the aforementioned insulating plates which normally surround a hub and jointly constitute a star-shaped or like carrier of resistance heaters. Another drawback of conventional heaters is that the resistance heaters require a relatively long interval of time to emit heat at the desired maximum rate, and that the interval of cooling of such resistance heaters is also long. Therefore, substantial quantities of heat and electrical energy are lost subsequent to completion of the circuit of one or more resistance heaters as well as upon disconnection of the resistance heater or heaters from the energy source. Heat energy which is supplied by the resistance heaters upon disconnection from the energy source is wasted.